Metal-insulator transition in perovskite oxides: A low-temperature perspective
- 1 January 1995
- journal article
- research article
- Published by Taylor & Francis Ltd in Advances in Physics
- Vol. 44 (1), 21-46
- https://doi.org/10.1080/00018739500101486
Abstract
A review is presented of recent experimental results of low temperature studies of composition driven metal-insulator transition in perovskite oxides of the ABO3 class. The evolution of physical properties like conductivity, tunnelling, density of states and magnetoconductivity has been studied at low temperatures (T < 10 K) because composition is varied so that the sample goes from the metallic state to the critical region through a weakly localized region. The results show an interesting interplay of disorder and correlation effects. Special attention has been paid to the critical region which is marked by very low conductivity and dσ/dT>0. In this region the following important observations emerge. (1) It is possible to have a metallic state [σ(T = 0) = σ 0 ≠ 0] with σ 0/σ Mott ≪ 1 and dσ/dT > 0. (2) At T < 2 K the conductivity follows a power law σ ∼Tν , where the exponent can be related to the finite frequency response of a zero temperature phase transition. (3) The Coulomb interaction plays a major role and evidence from tunnelling experiments suggests that a gap in the density of states at the Fermi level opens up continuously as the critical region is approached from the metallic side. (4) The magnetoconductivity is relatively smaller in the metallic and the weakly localized region (except the hole-doped LaMnO3 and related systems) but becomes very large at the critical region.Keywords
This publication has 40 references indexed in Scilit:
- Large magnetoresistance in La1−xSrxMnO3 and its dependence on magnetizationApplied Physics Letters, 1995
- Tunnelling studies on sodium tungsten bronzes near the metal-insulator transitionJournal of Physics: Condensed Matter, 1993
- Change of electronic structures with carrier doping in the highly correlated electron systemPhysical Review B, 1993
- Quantum corrections to the conductivity in a perovskite oxide: A low-temperature study of (0≤x≤0.75)Physical Review B, 1992
- Low-temperature electrical conductivity of Ta-compensated sodium bronze near the metal-insulator transitionPhysical Review B, 1991
- Metal-insulator transition in the compensated sodium bronze,Physical Review B, 1985
- Scaling Theory of Localization: Absence of Quantum Diffusion in Two DimensionsPhysical Review Letters, 1979
- Substitution du tungstene par le tantale dans les bronzes de tungstene NaxTayW1−yO3Materials Research Bulletin, 1979
- Transport properties of cubicnear the insulator-metal transitionPhysical Review B, 1976
- Interaction between the-Shells in the Transition Metals. II. Ferromagnetic Compounds of Manganese with Perovskite StructurePhysical Review B, 1951